The present invention relates to a toner replenishing device of an electrophotographic copying machine.
In a toner replenishing device of a popular type for a copying machine wherein two-component developers are used, a toner replenishing room located over a developer agitating chamber in the toner replenishing device is provided, at its opening, with a toner replenishing roller whose rotation causes toners to fall into the toner agitating chamber.
Following replenishing methods have so far been known as a conventional toner replenishing method.
(1) A toner replenishing method wherein a toner replenishing roller is provided with gauge grooves arranged on the surface of the roller in parallel with the roller axis, and excessive toners sticking to the roller surface are scraped off by a gauging blade arranged to be in a sliding contact to the roller surface, thus toner in a constant amount is replenished for each replenishment. (Japanese Patent Publication Open to Public Inspection No. 6872/1982 (hereinafter referred to as Japanese Patent O.P.I. Publication)).
(2) A toner replenishing method wherein a replenishing roller is provided thereon with spiral grooves and a scraper that is in a sliding contact with the roller surface scrapes off excessive toners, thus toner is replenished (Japanese Patent O.P.I Publication No. 56948/1975).
(3) A toner replenishing method wherein toner is fed out of a toner replenishing room by elastic fine bristles (metallic or nylon brush or the like) flocked on the surface of a toner replenishing roller and then are scraped off by a scraper (Japanese Patent O.P.I. Publication No. 60933/1979).
However, aforesaid conventional replenishing devices have had a problem that toner replenished into a developer agitating chamber cannot be mixed uniformly with carrier in the developer agitating chamber.
Namely, in the aforesaid methods (1), (2), and (3), scraped toners fall in a form of a clod and the clod stays in the agitating chamber, thus toners sometimes cannot be mixed uniformly with carrier.
An effective method to avoid such phenomenon is represented by the method (Japanese Patent O.P.I. Publication No. 7073/1987) wherein an opening of a toner replenishing room is so arranged as to contact with the developer in a developer agitating chamber and toner is conveyed by a carrier brush formed round a toner replenishing roller provided at the opening. In a small-sized copying machine, however, this method cannot be employed because of the restriction in terms of design; in many cases, the toner replenishing room has to be provided over the developer agitating chamber.